基于HHT提取重力固体潮的地震前兆信息

Hilbert-Huang Transformation(HHT)是一种新的非线性信号处理方法(Huang,1998).通过HHT对信号进行经验模态分解(empirical mode decomposition,简称EMD),能有效地把各种频率成分以本征模态函数(intrinsic mode function,简称IMF)形式从中分离出来.再对IMF序列进行Hilbert变换,可得到包含时间、频率、振幅的三维离散时频谱.它提供了非常清晰的局部细节时频特征,适合于描述具非线性非平稳性变化特征的信号.     

Analyzing vegetation dynamic trend on the Mongolian Plateau based on the Hurst exponent and influencing factors from 1982–2013

This study analyzed the spatial and temporal variations in the Normalized Difference Vegetation Index (NDVI) on the Mongolian Plateau from 1982–2013 using Global Inventory Modeling and Mapping Studies (GIMMS) NDVI3g data and explored the effects of climate factors and human activities on vegetation. The results indicate that NDVI has slight upward trend in the Mongolian Plateau over the last 32 years. The area in which NDVI increased was much larger than that in which it decreased. Increased NDVI was primarily distributed in the southern part of the plateau, especially in the agro-pastoral ecotone of Inner Mongolia. Improvement in the vegetative cover is predicted for a larger area compared to that in which degradation is predicted based on Hurst exponent analysis. The NDVI-indicated vegetation growth in the Mongolian Plateau is a combined result of climate variations and human activities. Specifically, the precipitation has been the dominant factor and the recent human effort in protecting the ecological environments has left readily detectable imprints in the NDVI data series.     

永安井数字化水位观测资料干扰

永安冷冻厂深井是东南沿海最深的地震地下水动态观测井,井深1 000.44 m,本文介绍了永安井的地质构造及正常动态变化规律,通过对永安井数字化水位观测资料的分析,总结日常观测过程中可能遇到的多种干扰因素,从自然因素、外界环境因素、人为干扰因素、仪器自身因素等典型表现,提高对非地震前兆干扰因素的识别,以便更好地排除干扰,提高仪器观测资料质量。     

南海第四纪东亚季风演化的粘土矿物指标

南海作为西太平洋最大的边缘海,记录着东亚季风的演化历史。本文在过去十多年研究积累的基础上,综述粘土矿物是记录南海东亚季风演化历史的良好指标。大量表层样品和多个沉积岩芯的研究显示,南海第四纪以来的蒙脱石主要是形成于周边岛屿火山岩的快速化学风化作用,记录了同时期的东亚夏季风气候条件;伊利石和绿泥石形成于周边大陆和岛屿的机械侵蚀作用,与强烈降雨引发的侵蚀能力或东亚冬季风相对寒冷的气候条件有关;而高岭石形成于周边陆地表面的强烈化学风化作用,指示地质历史时期累积的或第四纪同时期的温暖潮湿气候条件,但由于强烈的差异沉降作用,高岭石在南海主要沉积在近海陆架区域,在深海记录中多指示海平面变化的古环境特征。因此,我们提出蒙脱石/（伊利石+绿泥石）比值是南海第四纪东亚夏季风演化的良好指标,比值高代表夏季风温暖潮湿气候条件下增强的化学风化作用,比值低指示冬季风相对寒冷气候条件下减弱的化学风化作用,或是强烈降雨气候条件下增强的机械侵蚀作用。南海东亚夏季风演化的强弱与北半球夏季日射量基本呈线性关系,表明东亚季风演化的天文驱动机制,第四纪以来的长期演化显示南海在1200~400ka期间盛行夏季风,可能是受到赤道太平洋厄尔尼诺-南方涛动（ENSO）的影响。

     

Numerical simulation of groundwater flow patterns using flux as upper boundary

Since the 1960s, most of the studies on groundwater flow systems by analytical and numerical modelling have been based on given‐head upper boundaries. The disadvantage of the given‐head approach is that the recharge into and discharge from a basin vary with changes in hydraulic conductivity and/or basin geometry. Consequently, flow patterns simulated with given‐head boundaries but with different hydraulic conductivities and/or basin geometry may not reflect the effects of these variables. We conducted, therefore, numerical simulations of groundwater flow in theoretical drainage basins using flux as the upper boundary and realistically positioned fluid‐potential sinks while changing the infiltration intensity, hydraulic conductivities, and geometric configuration of the basin. The simulated results demonstrate that these variables are dominant factors controlling the flow pattern in a laterally closed drainage basin. The ratio of infiltration intensity to hydraulic conductivity (R_ic) has been shown to be an integrated pattern‐parameter in a basin with a given geometric configuration and possible fluid‐potential‐sink distribution. Successively, the changes in flow patterns induced by stepwise reductions in R_ic are identical, regardless of whether the reductions are due to a decrease in infiltration intensity or an increase in hydraulic conductivity. The calculated examples show five sequential flow patterns containing (i) only local, (ii) local–intermediate, (iii) local–intermediate–regional, (iv) local–regional, and (v) just regional flow systems. The R_ic was found to determine also whether a particular sink is active or not as a site of discharge. Flux upper boundary is preferable for numerical simulation when discussing the flow patterns affected by a change of infiltration, the hydraulic conductivity, or the geometry of a basin. Copyright © 2012 John Wiley & Sons, Ltd.     

多步法快速射线追踪与圆台型高精度走时外插计算

为更好地适应复杂构造的地震偏移成像,本文提出了一套快速射线追踪算法和一种高精度的走时外插计算方法.采用线性多步法的预测-校正公式求解射线追踪方程组,与传统的四阶Runge-Kutta法相比,提高了计算效率.在网格节点上的走时计算中,应用一种基于圆台的外插方法,该方法以射线的方向为轴确定圆台,将轴上的走时外插到圆台内的网格节点上.与传统的矩形体外插方法相比,圆台走时外插方法提高了计算精度,且具有更好的稳定性.另外,该方法利用稀疏分布的射线即可获得高精度的走时表,节省计算量,对复杂构造的偏移成像非常有利,尤其是三维偏移.最后通过逆散射偏移成像算例,验证了算法的有效性和适用性.

     

基于粒子图像测速技术的滑坡-涌浪两相运动分析系统

滑坡-涌浪灾害威胁沿河两岸居民生产生活安全和航道安全。当前尚缺乏同步提供流固两相运动矢量的相关物理试验分析系统,以深刻分析滑坡-涌浪产生机制。文章提出了基于流固两相识别的粒子图像测速（PIV）技术和试验实现方法。利用2560×1024像素的工业相机,该PIV技术可实现在3 m×1.5 m视窗下最小1.17 mm的空间分辨率和0.01 s内最小0.117 m/s的观测速度。同时,提出了与该系统方法有关的误差来源和克服相关问题的解决方法。利用相关硬件设施示范性构建了滑坡-涌浪两相运动观测平台,并编制了专门的解算软件。对三维柱体颗粒崩塌、二维柱体颗粒崩塌及其涌浪和水下崩塌-涌浪进行了展示性试验,取得了良好效果。该系统可以揭示广泛的岩土体及水体运动全过程,具有很好的应用前景;将为滑坡-涌浪及相关动力学领域研究提供强有力的研究工具。      

等值反磁通瞬变电磁成像技术及工程应用

为了实现对可溶岩区公路路线范围内的隐伏岩溶发育规模及形态进行高精度勘察,为后期处治设计提供翔实可靠的地质依据,在公路塌陷区域岩溶勘察中引入了一种新技术——等值反磁通瞬变电磁成像技术.文中首先对等值反磁通瞬变电磁成像技术的基本原理进行简述;然后论述了该方法的4种主要技术特点;紧接着对该方法的质量控制原则及数据处理流程等关键技术进行分析;最后利用该方法在惠清高速公路岩溶塌陷区探测中进行实际应用,成像结果准确地反映出了岩土界面的位置及变化形态,精确探测出了岩溶发育区的形态及规模,为后期塌陷区域的处治设计提供了可靠的基础资料.通过理论分析及实际应用结果表明:等值反磁通瞬变电磁法可对公路穿过区域隐伏岩溶发育情况进行精确成像,可快速准确的为岩溶塌陷区的后期处治设计提供基础资料.     

太阳能资源观测仪器（总日射表）性能测试方法

为了保证观测数据的准确性,必须建立全面的辐射表性能指标检测体系,对辐射仪器的性能指标进行测试.依据世界气象组织(WMO)和ISO 9060的相关规定,在总日射表检定规程的基础上,试验和研究总日射表的零偏移、分辨率、方向响应、非线性误差等性能指标.光电型总日射表与光热型总日射表相比有明显的光谱选择性,在光谱范围、响应时间、测量原理、结构材料等方面均存在不同,因此二者的测量方法也存在差异.在非线性测试中,双光源叠加法被用以取代传统的太阳模拟器法.研究表明,选择总日射表的方向响应误差来指定仪表在各方向上的性能以及规范总日射表的分类,比用余弦响应误差和方位响应误差有更多的优点.     

浅海桶基平台桶形基础结构设计分析

分析和描述了胜利石油管理局建成的CB20B浅海桶基平台桶形基础结构特点,讨论了结构设计应解决的主要问题、桶形基础结构型式和尺度、桶形基础结构设计以及强度和稳定性计算.